1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) panel sealing apparatus.
2. Description of the Related Art
Generally, LCD panels are manufactured as follows.
First, a seal material is coated at a periphery of a substrate except for liquid crystal injection openings by using a screen printing process. On the other hand, display spacers are dispersed onto a counter substrate by using a spacer dispersing apparatus. Then, the substrate is aligned with the counter substrate, and the seal material is hardened by applying heat or ultraviolet irradiation thereto. Then, liquid crystal is injected by a vacuum process from the liquid crystal injection openings into the gap between the substrate and the counter substrate.
Next, the liquid crystal injection openings are sealed by a seal material made of ultraviolet cured resin by an LCD panel sealing apparatus.
Finally, the outer surfaces of the substrate and the counter substrate are rinsed, and then, polarization plates are adhered thereto, thus completing the LCD panels.
In a first prior art LCD panel sealing apparatus (see JP-A-5-265013), a cassette for accommodating a plurality of laminated LCD panels is mounted on a block fixed at a bottom of a strut. Also, a holder for pushing the LCD panels is mounted slidably on the strut, and is driven by an air cylinder. This will be explained later in detail.
In the above-described first prior art LCD panel sealing apparatus, however, since there is only one pressurizing element, i.e., only one air cylinder, if the pressure within each LCD panel is non-uniform, it is impossible to make the pressure uniform. Particularly, when the size of LCD panels is changed, the pressure center of each LCD panel may be shifted to make this pressure more non-uniform. As a result, the gap between the substrate and the counter substrate of each LCD panel fluctuates, so that irregular display occurs, thus degrading the display quality.
In a second LCD panel sealing apparatus (see JP-A-8-262463), a plurality of holders for accommodating LCD panels are provided between two plates pushed by an air cylinder. Each of the holders has a flat bottom housing portion for holding one of the LCD panels where a spacer sheet is provided. As a result, the depth of the flat bottom housing portion is smaller than the thickness of the LCD panels. Also, protrusions are provided on the back surface of the holders, while recesses are provided on the front surface of the holders in back to back correspondence to the protrusions. Thus, the gap between the substrate and the counter substrate of each LCD panel is adjusted by the spacer sheet. This also will be explained later in detail.
Even in the above-described second prior art LCD panel sealing apparatus, however, since there is only one pressurizing element, i.e., only one air cylinder, if the pressure within each LCD panel is non-uniform, it is impossible to make the pressure uniform. As a result, the gap between the substrate and the counter substrate of each LCD panel fluctuates, so that irregular display occurs, thus degrading the display quality. In addition, when the size of LCD panels is changed, the holders per se have to be changed, which would increase the manufacturing cost.
It is an object of the present invention to provide an LCD panel sealing apparatus capable of making the pressure within each LCD panel uniform.
Another object is to decrease the manufacturing cost.
According to the present invention, in an LCD panel sealing apparatus, a cassette is provided to accommodate a plurality of laminated LCD panels into which liquid crystal is injected, and a plurality of pressurizing actuators are provided to pressurize the LCD panels. Thus, the pressurizing power of the pressurizing actuators are individually controlled to make the pressure within each LCD panel uniform.
Also, the cassette includes a guide unit for guiding the LCD panels in accordance with a size of the LCD panels. Thus, even when the size of the LCD panels is changed, the LCD panels can be easily accommodated in the cassette.